The market for UV curable printing inks and coatings is changing from the use of mercury light sources to light emitting diode (LED) light sources. The current commercial photoinitiators used in these formulations are optimized for the short wavelength emissions from mercury lamps, and are very inefficient at the longer wavelengths associated with LED light sources. There are some photoinitiators such as isopropylthioxanthone (ITX) and Michler's ketone that are effective at longer wavelengths.
However, ITX and Michler's Ketone are low molecular weight materials that can migrate out of food and beverage packaging materials, which have prepared with these photoinitiators, and into the food and beverages. There are polymeric versions of ITX available, but these are less effective than ITX itself. There is therefore a need in the marketplace for a photoinitiator which functions well under LED illumination, and which does not migrate from products after curing.